Embodiments of the present invention relate to lithium batteries and their packaging and fabrication methods.
Lithium batteries are used in applications that require a small battery with a high energy density such as, for example, portable electronics, medical devices and space systems. A typical lithium battery comprises one or more battery component layers that include electrolyte comprising lithium sandwiched between electrode layers, such as an anode, cathode, and/or current collectors. The battery component layers cooperate to store electrical charge and generate a voltage. Lithium batteries include larger scale structures, used for computer and car batteries, and thin film batteries in which the battery component layers are thin films which have thicknesses of less than 100 microns. Lithium batteries can also either be used individually or multiple batteries can be stacked together to provide more power or more energy.
The lithium batteries are packaged in protective packages to protect the battery component layers from the external environment to reduce their degradation over time. Battery component layers containing lithium can degrade when exposed to carbon monoxide, carbon dioxide, oxygen, nitrogen, moisture or even organic solvents present in the atmosphere. Thus protective packaging is used to protect the battery component films from the external environment. Suitable packaging assemblies are, for example, described in commonly assigned U.S. Pat. No. 7,846,579, filed on Mar. 25, 2005, entitled “Thin Film Battery with Protective Packaging”, U.S. patent application Ser. No. 12/963,610, filed Dec. 8, 2010, entitled “Battery with Protective Packaging”, and U.S. patent application Ser. No. 12/454,255 filed May 13, 2009, entitled “Thin Film Battery with Protective Packaging”, all of which are incorporated by reference herein and in their entirety. However, even these advanced packaging structures and packaging methods can be improved upon to reduce long term degradation of the charging and discharge properties of lithium batteries.
Thus still further developments and improvements in packaging technology and methods of fabrication of lithium batteries, including large scale and thin film lithium batteries, are continuously being sought.